Stabilization of fatty acid compounds



ratented Apr. 11, 1939 UNHTED STATES PATENT OFFICE STABILIZATION F FATTY ACID COMPOUND No Drawing. Application March 23, 1938, Serial No. 70,408

4 Claims.

The present invention relates to improvements in the stabilization of compounds containing a fatty acid radical as for example, fatty acid derivatives such as vegetable oils, and more particularly soap or soap products made from fats which ordinarily deteriorate or develop rancidity in a relatively short time.

Among the objects of the present invention is the inhibiting or retarding the deterioration of fatty acid derivatives such as for example vegetable oils and soaps.

Another object of the invention is the preparation of a new and improved vegetable oil or soap.

According to the present invention it has been found that by the incorporation of a small quantity of a thiourea in the fatty acid compound as for example vegetable oil or soap, a product of improved stability against deterioration and development of rancidity is thereby produced.

More particularly the present invention coniprises the use in the stabilization of fatty acid derivatives as vegetable oils, soap and soap products, of thioureas possessing the'general formula wherein R is hydrogen, an alkyl, an alkylene, aralkyl, aryl, alicyclic and acyl radical.

erties of the preferred class of materials, the following procedure was employed:

A substantially neutral soap was prepared by saponifying a mixture of substantially three parts of an edible tallow and substantially one part of coccanut oil with sodium hydroxide. Substantially 0.1% based on the weight of the soap (0.005 gram) of one of the preferred stabilizers was incorporated therein by a suitable means. Five grams of the treated soap were placed in a 250 c. c. iodine flask, a piece of filter paper saturated with water was torn to small pieces and placed in the flask. The flask was then tightly stoppered and placed in an oven maintained at a constant temperature of 50 C. At the end of each day the color of the soap under test was noted, also the stopper was removed and any odor indicative of rancidity noted. Similar tests were carried out with the same soap but to which no stabilizer was added, and the As one method of testing the stabilizing propperiods of stability compared as hereinafter set forth.

As specific examples and as specific embodiments of the present invention but in no sense to be understood as limitative of the scope of the a invention, the following thioureas were incorporated in a soap of the above characteristics and tested in the manner described. The period of stability or the period during which the soap did not develop racidity or substantially discolor is given in the following table.

Table I an P. s a z ng or 0d of Stabilizing agent agent based stability on the weight in days the soap aQB-Hydroxy ethyD-fi-phenyl thio- 2o urea 0.1 17 a, a-Diw-hydroxyethyl)-8-pheuyl thiourea 0.1 19 Thiocarbanilide 0. 1 18 Tri henyl guanyi thiourea. 0. 1 21 S-d (crtho-toiyl) thiourea 0.1 21 'lri-ortho-tolyl guanyl thiourea 0.1 21 25 o-Phenyl-B-parmphenetyl thiourea 0. 1 21 gglrthg 0.1 21

y Edionzo l I2 Ethylene irhenyl di- 0. l 18 Mono-sooty 0. 1 14 a-Di-acetone-B- henylthlourca 0.1 12 S-diEo-biphenyl thiourea 0.1 18 S-di p-lrydrox phenyl) thiourea 0.1 7 S di(p-ehior p enyl) thiourea 0. 1 l9 a-(p-Hydroxy ethyD-a-b e n z y 2-8- phenyl thiourea 0. 1 Y .12 Sumo-among phenyl) thiourea... 0. 1 20 S-dibenzyl t iourea 0. 1 l1 S-dicyciohexyl thiourea 0.1 18 S-di(2,6 dimethyl phauyD-thiourea. 0. l 12 hiourea 0. 1 6 q-E thyl-a-phenyl-fl-phenyl thiourea; 0. 1 12 a-(p-Hydroxy othyl)-ap h c n y 1-6- in 0. l 18 0. 1 Over 14 0. 1 Over 14 lizcr 3 to 4 4 If convenient or desirable mixtures of thioureas may be employed to good advantage as stabilizers of fatty acid derivatives as for example soap or soap products. Thus, any of the above thioureas and equivalents thereof may be mixed in suitable proportions and employed as stabilizers of fatty acid compounds such for example as vegetable oils and soaps. As one specific example 0.1% by weight on the above soap of a mixture of substantially equal parts by weight of symmetrical p-hydroxy ethyl thiourea and thiocarbanilide was incorporated in the soap obtained from tallow and cocoanut oil described above, and tested in ferred class of stabilizing agents may be moor-- porated in a fatty acid. compound such as a vegetable oil, for example cottonseed oil. As a means of testing the stabilizing action thereof the treated oil is heated in an open flask for several days in an oven maintained at 50 C. At the end of each day samples of the aged oil are tested in a manner analogous to that described by D. H. Wheeler, Oil and Soap, vol. 9, page 93, 1932. Thus, five grams of cottonseed oil are dissolved in 50 c. c. of solvent mixture percent of glacial acetic acid, 40 percent of chloroform) and 1 c. o. of saturated potassium iodide solution added. After exactly one minute from the time of the addition of the potassium iodide, c. c. of water are added and the liberated iodine titrated with 0.01 N sodium thiosulfate. Starch is added towards the last as indicator. The titration in cubic centimeters is a measure of the peroxide formation and consequently a measure of the stability of the oil. The titration figures obtained on heating the above oil for 1, 2, 3 and 4 days at 50 C. in the absence of and in the presence of 0.1% by weight of the new class of stabilizing agents is given in Table II. The oil before heat- From the data set forth in Table II it isshown that the preferred class of compounds possess exceptional stabilizing properties when incorporated in fatty products, for example vegetabl oils.

The amount of the selected one or mixture of the preferred substances which may be added to the ordinary soap, or soap stock, or ingredients used in the manufacture thereof, for eflecting desired result, may be varied, but in general it will be found that good results may be obtained by adding, upon a weight basis, from0.0l% to 1.07;, of the stabilizing agent to the soap or soap stoc In utilizing the present invention, the stabilizing agent may be introduced at any stage of the process of soap manufacture. For example, after the fatty acid has been obtained in the usual manner and has been saponified to produce a soap stock the products comprising the preferred stabilizers may be incorporated therein. The soap product may then be dried in the usual manner and may be marketed in cakes, flakes or any other form as may be desired. Further, if desirable the stabilizing agent may be incorporated into the dry soap in the well known crutching process. Moreover, the stabilizing agent may conveniently be added to the oils, fats or fatty acids before saponification. Again the thioureas of the present invention may be employed in conjunction with soaps and fatty oils broadly as stabilizers thereof.

Again other methods of testing the stability of fatty acid compounds than those specifimlly disclosed may be employed, as is well known to those skflled in the art to which the present invention pertains.

The present invention is limited solely by the following claims attached hereto as part of the specification.

What is claimed is:

1. A soap containing a small proportion of a stabilizer against deterioration and development of rancidity consisting of a substituted thiourea, the substituents of which are selected from the group of radicals consisting of non-substituted aryl, biaryl, h'aloaryl, alkaryl, alkoxyaryl, alkyl, aralkyl, hydroxyalkyl, alicyclic, acyl, aracyl, oxyalkyl and guanyl.

2. A soap stabilized against deterioration and the development of rancidity by having incorporated therein a small proportion of (B-hydroxy ethyl) p-phenyl thiourea.

3. A soap stabilized against deterioration and the development of rancidity by having incorporated therein a small proportion of a mixture of a s-diQS-hydroxy ethyl) thiourea and thiocarbanilide.

4. A soap stabilized against deterioration and the development of rancidity by having incorporated therein a small proportion of thiocarbanilide.

GEORGE D. MARTIN. 

